Justin Wilson said he is 'shocked' at the news that former teammate AJ Allmendinger and RuSPORT have parted ways.
The American has split with RuSPORT, with whom he won the Atlantic Championship in 2003, and with whom he graduated to Champ Car in 2004 and won Rookie of the Year title.
Last year, Allmendinger scored his first pole with the team and also measured up well to more experienced teammate Wilson.
"I like and respect him as a friend, and I liked having him as a teammate," said Wilson. "He's very, very fast, and I liked having him to measure myself against, and I'm really sorry that it's ended this way. I'm shocked it's happened mid-season, and that's really all I can say on the matter."
Carl Russo, owner of the RuSPORT team paid tribute to his former driver tonight in a Champ Car teleconference. He said: "With the state of open-wheel motorsport at the time, I guess it's possible that if not for RuSPORT, AJ might not be where he is today.
"But I can tell you for certain that if not for AJ, we wouldn't be where we are today. His talent, his efforts, his drive has certainly helped the team get to this point, and I consider him to be and still consider him to be amongst the most talented racers I have ever seen.
"Having said that, there are times as you grow a business and grow a team where perhaps the growth curves of both the driver and team might be better suited to a change in environment.
"We came to that decision basically a couple of days ago and decided to move forward. Obviously, I'm looking forward to AJ getting into an environment that enables him to continue to grow. We will do the same here at RuSPORT."
Russo went on to explain his ambitions for Allmendinger's replacement, 2002 Champ Car title-winner Cristiano da Matta. "Both AJ and Cristiano are multiple champions at multiple levels," Russo said. "The difference is at the margins.
"Cristiano, as you know, is a former champion. He's both a great person in and out of the car. But one of the things that we think we're going to benefit from is the wealth of technical expertise, the background, the Formula One experience, et cetera, to help us continue to drive the technical side of the equation forward.
"We have we think a very strong technical staff. We're looking forward to benefiting from Cristiano's experience there.
"Having said that, you know, make no mistake about it, we think Cristiano is a great racer, a great qualifier, and somebody that's great speed, and showed a lot fighting his way back into the paddock at the beginning of this year. So we're looking forward to him to go to the front immediately."
A thrilled da Matta explained: "Everything happened so quickly. It was just a great opportunity. You know, I'm on my sixth year on Champ Car racing, and I've only really had a chance to win and to go after the championship in two of my years.
"I feel like with RuSPORT now, I'm going to be able to go on and be a contender for the race win every weekend. I think it's just a great opportunity for me.
"What I really appreciate about RuSPORT is how hard they try just going after Newman/Haas and Sebastien [Bourdais]. I like this.
"We'll do whatever it takes to go after these guys and maybe one day we're going to obviously eventually beat them. I think that's the type of mentality I have, too, so I think we'll fit very well together.
"I don't know Justin extremely well, but I know him a bit. We've been always good friends. We've been always very respectful in the racetrack, out of the racetrack. I'm sure from what I know from his personality and I know from my personality, we're going to have a very good time working together."
Wilson himself said: "I had a great time with AJ, at the track and away from the track. I considered him a good friend. Cristiano I don't know so well yet, but I think we'll get on well, I think his feedback will be good and I know he'll be fast. We should get on fine: I have no worries on that score."